I. Field of the Invention
This invention relates generally to an auxiliary wheel/axle assembly for a work-type vehicle and more particularly to an improved tag wheel/axle assembly attachable to the rear end of a vehicle and which can be selectively deployed into a ground-engaging disposition or retracted to an elevated disposition where the wheels straddle the sides of the truck frame.
II. Discussion of the Prior Art
To prevent undue deterioration of highhways and other road surfaces, states and/or the Federal Government impose weight restrictions on vehicles traveling over those highways. Most commonly, the weight restrictions are measured in terms of load per axle and the overall spacing between axles. It is readily apparent that if the number of axles of the truck and the spacing thereof can be increased, a given vehicle may carry a higher payload than would otherwise be permitted. Included in the prior art are numerous devices designed to achieve the foregoing end. For example, in the arrangement shown in the Prichard U.S. Pat. No. 3,112,100, a tag wheel assembly is attached to the rear of a ready-mix concrete truck and the wheels are mounted on a transversely extending axle, the axle being joined by elongated arms which are pivotally coupled to opposed sides of the truck frame. A hydraulic cylinder is operatively coupled to the truck body and to the arms and when its piston is retracted, the tag axle assembly is elevated through pure rotation of the non-articulated arms to a substantial height above the ground. In retracted mode, the wheels are above the center of gravity, making the vehicle top-heavy. Also, the machine constructed in accordance with the Prichard patent can only be unloaded when the tag axle is in its elevated disposition which may not be legally unloaded when the ready-mix truck is on a Federal highway.
In the case of the Silbernagel U.S. Pat. No. 4,314,709, when the tag axle assembly is elevated, it interferes with thee unloading of the ready-mix concrete truck. Still other designs, such as is disclosed in the Allison et al U.S. Pat. No. 4,082,305, do not allow the auxiliary wheels to be lifted to a sufficiently high level to clear curbs or rough terrain when leaving the road and entering the construction area.